Mitsubishi Heavy Industries V Multi FDC71VNX Technical Manual page 243

Error code
E57
Remote control:
1. Applicable model
Models SRC40-60
2. Error detection method
• Judge insufficient refrigerant
amount by detecting the
temperature differnce between
indoor heat exchanger (Thi-R)
and indoor return air (Thi-A).
3. Condition of error displayed
When the insufficient refrigerant
amount is detected 3 times
within 60 minutes.
4. Presumable cause
• Defective indoor heat
exchanger temperature sensor
• Defective indoor return air
temperature sensor
• Defective indoor unit control
PCB
• Insufficient refregerant
amount
Note: When the compressor speed is 50 rps or under at 5 minutes after the start of compressor or the completion of defrost operation, the low refrigerant protection
control judges, by detecting the difference between the indoor heat exchanger temperature (Thi-R) and the indoor return air temperature (Thi-A), that it is in the
state of gas leakage, and stops the compressor.
Cooling: Indoor return air temperature (Thi-A) – Indoor heat exchanger temperature (Thi-R) ≧ 4 degC
Heating: Indoor heat exchanger temperature (Thi-R) – Indoor return air temperature (Thi-A) ≦ 6 degC
LED Green Red
Keeps flashing Stays OFF
Indoor
5. Troubleshooting
Diagnosis
Is the
service valve fully
opened?
YES
Are the
connections of indoor
heat exchanger and/or return air
temperature sensor
connectors OK?
YES
Are the
characteristics of indoor heat
exchanger and/or return air
temperature sensor
OK?
YES
Is the low
pressure during operation
normal?
Indoor heat exchanger, return air temperature sensor
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short-circuit)
0
242
-
Insufficient refrigerant amount
Content
or detection of service valve closure
(Models SRC40-60 only)
NO
NO
NO
NO
YES
5k at 25°C
10 20 30 40 50
Temperature (°C)
-
'19 • PAC-T-327
Countermeasure
Open fully.
Correct indoor heat
exchanger, return air
temperature sensor
connector connections.
Defective indoor heat
exchanger, return air
temperature sensor
➞ Replace.
Charge refrigerant.
Defective indoor unit
control PCB ➞ Replace.
(Defective indoor heat
exchanger, return air
temperature sensor input
circuits)